The present invention relates to a communication system for mutually connecting a plurality of repeating devices (or relay devices) each of which has one or more node terminals connected thereto, so that data communication is carried out between one node terminal and the other node terminal, between one repeating device and the other repeating device or between the node terminal and the repeating device. More particularly, it relates to a communication system that, for example, even when the data communication is executed between the node terminals, communication data can be certainly transmitted from one node terminal as a xe2x80x9csenderxe2x80x9d to another node terminal as a xe2x80x9cdestinationxe2x80x9d alias receiver without reducing its data volume transmitted per unit time. Further, the present invention also relates to a data format to be used in such a communication system.
Additionally, the present invention relates to the communication system by which it is possible to simplify an address management therein and allow an additional new node terminal to be communicated with the existing node terminals instantly, thereby providing the communication system which is capable of coping with, namely, xe2x80x9cplug and playxe2x80x9d function.
Conventionally, there is a known communication system which connects a plurality of repeating devices with each other, each of the repeating devices having one or more node terminals connected thereto, so that data communication can be carried out among the respective node terminals, among the respective repeating devices, or among the node terminals and the repeating devices.
For example, when the communication data is transmitted from one node terminal as the sender to a specific node terminal as the address in the above-mentioned conventional communication system, it has been taken place to provide a communication frame containing commands and data as objects to be transmitted with a sender/destination description area for designating information of the sender and the destination. In detail, in case of designating a sender, both an address of the node terminal as the sender and an additional address of a repeating device involving the specified node terminal are described in the sender/destination description area. Again, in case of designating the destination, both an address of the node terminal as the receiver and an additional address of a repeating device involving the destined node terminal are together described in the sender/destination description area similarly. In this way, the communication data is transmitted from the specified node terminal as the sender to the designated node terminal as the destination in the conventional communication system.
In accordance with such a designating method in the above-mentioned conventional communication system, however, when it is required to exchange data between the node terminals, the addresses of the node terminals and the addresses of the repeating devices involving the node terminals have to be described in the sender/destination description area established in the communication frame. Consequently, since a bit length that the sender/destination description area occupies in the communication data is increased, the conventional method contains a problem of difficulty to increase data transfer quantity per unit time.
It is therefore an object of the present invention to provide a communication system which is capable of transmitting communication data from a sender to a nominated destination without reducing data volume transmitted per unit time certainly, and a data format used in such a communication system.
It is an additional object to provide a communication system which is capable of simplifying management of addresses stored in the system and bringing a new node terminal, which is intended for additional connection with the repeating device, into its communicable condition instantly, in other words, xe2x80x9cplug and playxe2x80x9d function.
In accordance with the present invention, there is provided a communication system comprising a plurality of repeating devices each having one or more node terminals connected thereto, the repeating devices being connected with each other through a data transmitting path, whereby data communication is carried out between the node terminals, between the repeating devices, or between the node terminal and the repeating device, the repeating devices each comprising:
terminal address storing means for storing terminal addresses established to inherent values for the node terminals, respectively;
device address storing means for storing a device address established to an inherent value for the repeating device concerned and established to be distinguishable from the terminal addresses; and
header information adding means for adding sender/destination information of a sender or a destination to communication data which has been fed from the repeating device concerned or the one or more node terminals connected thereto, the header information adding means further sending the communication data with the sender/destination information toward the data transmitting path;
wherein the sender/destination information added to the communication data by the header information adding means includes either the terminal address stored in the terminal address storing means or the device address stored in the device address storing means.
With the above-mentioned arrangement, in operation, the header information adding means adds the sender/destination information to the communication data transmitted from the repeating device or the node terminal. Thereafter, the header information adding means sends the communication data with the sender/destination information toward the data transmitting path. Since the sender/destination information is constituted by either one of the terminal address stored in the terminal address storing means or the device address stored in the device address storing means, it is possible to shorten a bit length required for designating the address as a whole, comparing with the conventional system where both addresses of the repeating device and the associating node terminal(s) are incorporated to the communication data in order to designate the addresses of the sender/destination. Thus, it is possible to transmit the communication data from the sender to the nominated destination without reducing the data volume transmitted per unit time, certainly.
In accordance with the present invention, there is also provided a communication system comprising a plurality of repeating devices each having one or more node terminals connected thereto, the repeating devices being connected with each other through a data transmitting path, whereby data communication is carried out between the node terminals, between the repeating devices, or between the node terminal and the repeating device, the repeating devices each comprising:
terminal address storing means for storing terminal addresses established to inherent values for the node terminals, respectively;
device address storing means for storing a device address established to an inherent value for the repeating device concerned and established to be distinguishable from the terminal addresses; and
header information adding means for adding sender/destination information of a sender or a destination to communication data which has been fed from the repeating device concerned or the one or more node terminals connected thereto, the header information adding means further sending the communication data with the sender/destination information toward the data transmitting path;
wherein the sender/destination information added to the communication data by the header information adding means includes:
an identifier of short bit length, which is used in identifying which of the node terminal and the repeating device the sender or the destination of the communication data is related to; and
either one of the terminal address stored in the terminal address storing means and the device address stored in the device address storing means.
In accordance with the present invention, there is also provided a communication system comprising a plurality of repeating devices each having one or more node terminals connected thereto, the repeating devices being connected with each other through a data transmitting path, whereby data communication is carried out between the node terminals, between the repeating devices, or between the node terminal and the repeating device, the repeating devices each comprising:
terminal address storing means for storing terminal addresses established to inherent values for the node terminals, respectively;
device address storing means for storing a terminal address of one node terminal as a device address, the one node terminal being selected from the one or more node terminal in accordance with a predetermined selection rule; and
header information adding means for adding sender/destination information of a sender or a destination to communication data which has been fed from the repeating device concerned or the one or more node terminals connected thereto, the header information adding means further sending the communication data with the sender/destination information toward the data transmitting path;
wherein the sender/destination information added to the communication data by the header information adding means includes:
an identifier of short bit length, which is used in identifying which of the node terminal and the repeating device a sender or a destination of the communication data is related to; and
either one of the terminal address stored in the terminal address storing means and the device address stored in the device address storing means.
Also in the above-mentioned arrangement, the header information adding means operates to add the sender/destination information to the communication data transmitted from the repeating device or the node terminal. Thereafter, the header information adding means sends the communication data with the sender/destination information toward the data transmitting path. Since the sender/destination information is constituted by the identifier of short bit length, which is used in identifying which of the node terminal or the repeating device the sender or the destination of the communication data does relate to and either the terminal address stored in the terminal address storing means or the device address stored in the device address storing means, it is also possible to shorten a bit length required for designating the address as a whole, comparing with the conventional system where both addresses of the repeating device and the associating node terminal(s) are incorporated to the communication data in order to designate the addresses of the sender/destination. Consequently, it is possible to transmit the communication data from the sender to the nominated destination without reducing the data volume transmitted per unit time, certainly.
In the above-mentioned arrangement, preferably, the predetermined selection rule is established on a basis of a set value of the terminal address optionally.
According to the present invention, there is also provided a data format to be used in a communication system where a plurality of repeating devices each having one or more node terminals connected thereto are connected with each other through a data transmitting path, whereby data communication is carried out between the node terminals, between the repeating devices, or between the node terminal and the repeating device, the data format comprising:
an address description area established in a communication flame for communication data as an object to be transmitted, for describing either a terminal address established to an inherent value for each of the node terminals or a device address established to an inherent value for each of the repeating devices and distinguishable from any terminal address of the node terminals.
Further, there is also provided a data format to be used in a communication system where a plurality of repeating devices each having one or more node terminals connected thereto are connected with each other through a data transmitting path, whereby data communication is carried out between the node terminals, between the repeating devices, or between the node terminal and the repeating device, the data format comprising:
an identifier description area established in a communication flame for communication data as an object to be transmitted, for describing an identifier of short bit length used in identifying which of the node terminal and the repeating device a sender or a destination of the communication data is related to; and
an address description area established in the communication frame, for describing either a terminal address established to an inherent value for each of the node terminals or a device address established to an inherent value for each of the repeating devices.
In common with the above-mentioned data formats, it is also possible to shorten a bit length required for designating the address as a whole, comparing with the conventional system where both addresses of the repeating device and the associating node terminal(s) are incorporated to the communication data in order to designate the addresses of the sender/destination. Consequently, it is possible to transmit the communication data from the sender to the nominated destination without reducing the data volume transmitted per unit time, certainly.
In the later data format, preferably, the device address has a terminal address of one node terminal established as a device address, the one node terminal being selected from the one or more node terminals in accordance with a predetermined selection rule.
In this case, owing to the diversion of the terminal address of the selected note terminal, the establishing management for the device terminals can be simplified.
More preferably, the predetermined selection rule is established on a basis of a set value of the terminal address optionally.
According to the present invention, there is also provided a communication system comprising a plurality of repeating devices each having one or more node terminals connected thereto, the repeating devices being connected with each other through a data transmitting path, whereby data communication is carried out between the node terminals, between the repeating devices, or between the node terminal and the repeating device, the repeating devices each comprising:
terminal address storing means for storing terminal addresses established to inherent values for the node terminals, respectively; and
communication propriety storing means for storing respective communication propriety conditions as to whether each of the node terminals connected to the repeating device concerned is under its communicable or incommunicable condition;
wherein the terminal addresses stored in the terminal address storing means include a terminal address with respect to an additional node terminal which may be connected to the repeating device concerned additionally, while the communication propriety condition of the additional node terminal stored in the communication propriety storing means is initialized to its incommunicable condition.
In this case, since an inherent terminal address is previously established with respect to the additional node terminal which may be connected to the repeating device concerned additionally and since the communication propriety condition of the additional node terminal is initialized to its incommunicable condition, it is possible to realize the communication system having the simplified address management. Moreover, since the communication system of the invention is constructed irrespective of connection of the additional instruments on the assumption that all of the existing communication terminals including the additional instruments are connected to the system, it is possible to accomplish the design of hardware and software with ease.
In the above-mentioned communication system, preferably, each of the repeating devices further includes:
communication propriety rewriting means for rewriting the communication propriety condition of the additional node terminal from its incommunicable condition to its communicable condition when the additional node terminal is connected to the repeating device concerned.
In operation, when the additional node terminal is connected to the repeating device concerned, then the communication propriety rewriting means rewrites the communication propriety condition of the additional node terminal from the incommunicable condition to the communicable condition. Therefore, even if the additional instruments are additionally connected to the repeating devices after being connected to the communication system, it is possible to eliminate some steps of providing such additional instruments with new addresses and allows the system to recognize each of the additional instruments as one of some functional instruments connected with the repeating devices instantly. As a result, it is possible to realize the communication system which is capable of eliminating the complicated procedure for giving the addresses and bringing the additional instruments into their communicable conditions instantly, namely, effecting the plug and play function.
In the above-mentioned communication system, preferably, each of the repeating devices further comprises incommunicable notice replying means for replying an incommunicable notice representing that the node terminal concerned is under the incommunicable condition toward a sender of the communication data when receiving communication data directed to a node terminal under its incommunicable condition.
According to the present invention, there is also provided a communication system comprising a plurality of repeating devices each having one or more node terminals connected thereto, the repeating devices being connected with each other through a data transmitting path, whereby data communication is carried out between the node terminals, between the repeating devices, or between the node terminal and the repeating device, the repeating devices each comprising:
terminal address storing means for storing terminal addresses established to inherent values for the node terminals, respectively; and
communication propriety storing means for storing respective communication propriety conditions as to whether communication terminals including the repeating device and the one or more node terminal connected to the repeating device are under respective communicable or incommunicable conditions;
wherein the terminal addresses stored in the terminal address storing means include a terminal address with respect to an additional node terminal which may be connected to the repeating device concerned additionally, while the communication propriety condition of the additional node terminal stored in the communication propriety storing means is initialized to its incommunicable condition.
Also in this case, since an inherent terminal address is previously established with respect to the additional node terminal which may be connected to the repeating device concerned additionally and since the communication propriety condition of the additional node terminal is initialized to its incommunicable condition, it is possible to realize the communication system having the simplified address management. Moreover, since the communication system of the invention is constructed irrespective of connection of the additional instruments on the assumption that all of the existing communication terminals including the additional instruments are connected to the system, it is possible to accomplish the design of hardware and software with ease.
In the present invention, preferably, each of the repeating devices further comprises:
communication propriety rewriting means for rewriting the communication propriety condition of the additional node terminal from its incommunicable condition to its communicable condition when the additional node terminal is connected to the repeating device concerned.
Similarly, when the additional node terminal is connected to the repeating device concerned, then the communication propriety rewriting means rewrites the communication propriety condition of the additional node terminal from the incommunicable condition to the communicable condition. Therefore, even if the additional instruments are additionally connected to the repeating devices after being connected to the communication system, it is possible to eliminate some steps of providing such additional instruments with new addresses and allows the system to recognize each of the additional instruments as one of some functional instruments connected with the repeating devices instantly. As a result, it is possible to realize the communication system which is capable of eliminating the complicated procedure for giving the addresses and bringing the additional instruments into their communicable conditions instantly, namely, effecting the plug and play function.
More preferably, the communication propriety storing means operates to rewrite the communication propriety condition of the communication terminal concerned, from its communicable condition to its incommunicable condition when any one of the communication terminals falls into its incommunicable condition.
In the above-mentioned communication system, it is also preferable that each of the repeating devices further comprises incommunicable notice replying means for replying an incommunicable notice representing that the node terminal concerned is under the incommunicable condition toward a sender of the communication data when receiving communication data directed to a node terminal under its incommunicable condition.